With a security freeze, lenders and businesses cannot get access to your credit files or your credit scores without your authorization. This means they aren't likely to issue new credit. That in turn greatly reduces the chance that a thief will be able to get credit in your name and damage your credit profile.

Until now, if you wanted to freeze your credit reports, you had to live in a state where the practice was allowed. Laws in 39 states and the District of Columbia have given consumers that option.

For details on security freeze laws, use Consumers Union's "Guide to Security Freeze Protection" at www.FinancialPrivacyNow.org. Consumers Union has compiled a detailed list of each state's law, including when and how you can lift the freeze. The site also provides direct links to the three credit bureaus' security freeze information. Just be sure to double check with each bureau when placing a security freeze to make sure you are sending the right information.

To implement a freeze, you will have to send a certified letter to each of the three major credit bureaus. When applying for a security freeze, you get a PIN (personal identification number) or password that you will need to use to lift the freeze from your file. The security freeze will remain in place until you request that it be permanently removed or temporarily lifted for a specific time or for a particular creditor or company (for example, an employer or landlord wanting to check your credit history).

Experian enables consumers to lift the freeze within 15 minutes by making a request online or by phone. Equifax and TransUnion allow consumers to lift the freeze by phone or by mail, but the request can take up to three days from the date of receipt to go into effect.

Also be aware that a security freeze generally does not apply to your existing accounts. Existing creditors or affiliate companies can still access your files. A security freeze also doesn't prevent companies from peeking at your credit files to prescreen you for additional credit.

There is a catch to this security freeze protection - cost.

For residents of the states without security freeze laws, the three credit bureaus will provide a freeze free for identity theft victims. Victims also will not be charged to lift the freeze. For everyone else, there's a $10 fee for each bureau to initiate the freeze and $10 to lift it temporarily or remove it altogether.

In all, that's $30 to place a freeze on your credit files at all three bureaus. If you need to apply for credit later, you have to pay another $30 to unlock your files for a lender. If you don't plan properly, you would have to pay $30 each time you want a creditor to view your credit files.

In the states where a law is in place and lower fees are mandated, the credit bureaus must offer the freeze at the lower price.

Consumers Union is pushing to get the credit bureaus to charge all consumers no more than $5 to initiate and temporarily lift a security freeze and no fee to remove the safeguard altogether.

Considering the recent spate of lost and stolen data on millions of consumers, Congress needs to mandate that everyone be allowed to initiate a security freeze at no charge. After all, we know identity theft is a huge problem.

Michelle Singletary is a Washington Post business writer. She can be reached at singletarym@washpost.com or c/o The Washington Post, 1150 15th St. NW, Washington, D.C. 20071.